Pituitary transplantation and human formation

Pituitary transplantation and human formation is the medical process at the center of the transformation of Sharik into a humanized being. Conceived as an investigation of rejuvenation and the pituitary’s function, the experiment instead produced what Professor Preobrazhensky called total humanization. Its outcome exposed a gap between the power to create a human form and the ability to determine what kind of person would emerge: the new being’s development was tied not to an abstract ideal but to the particular human source of the transplanted organs.

Experimental Aim and Operation

The experiment began with a male dog estimated to be about two years old. On December 23, at 8:05 in the evening, Professor Preobrazhensky began an operation he regarded as the first of its kind in Europe. The plan combined transplantation of the pituitary and testes to investigate their functional viability in a host organism and their possible role in cellular rejuvenation. The human organs came from a 28-year-old man who had died four hours and four minutes before the operation; they had been kept in sterilized physiological fluid.

The procedure therefore joined two questions that later proved to have different answers: whether transplanted organs could function in a new host, and whether that function could produce rejuvenation. The experiment did demonstrate a powerful effect, but the decisive result was not a simple restoration of youth. Instead, the transplanted pituitary initiated a transformation that made the dog increasingly human.

From Animal to Humanized Being

The early change became visible in speech and social behavior. In his case notes, Doctor Bormenthal recorded that the subject could sustain conversation and had begun putting his hands in his pockets. He also noted attempts to teach him not to swear and his whistling of a street song. These signs suggested that humanization was taking shape through acquired language and recognizable habits, not merely through a change in outward appearance.

Bormenthal proposed that the implanted pituitary had activated the speech center in the canine brain, releasing words that had accumulated during the dog’s earlier life. On this account, the operation had stimulated development rather than created an entirely new brain. The words first spoken were, he hypothesized, street language the dog had heard and stored as sensory information. His speculation linked the new human speech to the animal’s prior experience, making the transformation a continuation of the dog’s life as well as a radical change in its form.

The notes also record a broader scientific interpretation: the pituitary seemed to determine human appearance, and its hormones could be understood as central to the organism’s image. Bormenthal described the creation of a new human entity through surgery, while treating the result as evidence about the pituitary’s role and the brain’s development. The claim of discovery was ambitious, but the experiment’s immediate evidence remained a particular, difficult subject rather than a controlled demonstration of an ideal human type.

A Revised Diagnosis

On January 8, after prolonged uncertainty, Preobrazhensky accepted that the operation had not induced rejuvenation. His diagnosis was that pituitary transplantation caused total humanization, a conclusion emphatically marked in Bormenthal’s notes. The revision did not make the discovery seem smaller to him: he still regarded it as a major scientific finding, but its significance had shifted from extending life to explaining the formation of human identity and appearance.

The distinction mattered because the original aim had included cellular rejuvenation, while the observed result was the emergence of a humanized individual. The operation had not simply made the dog younger or more vigorous. It had brought a new human entity into being, with speech and conduct that required the experimenters to confront the practical and ethical consequences of their work.

The Donor and the Limits of Creation

Preobrazhensky’s later explanation made the donor’s identity central to the outcome. He argued that even if he could transplant the pituitary of Spinoza—or another person—and turn a dog into a highly intelligent being, there would be no reason to manufacture artificial geniuses when human beings could be born naturally. He contrasted the hoped-for improvement of humanity with the actual result, which he associated with Klim Chugunkin, the donor whose organs had been used in the experiment.

The professor described Chugunkin as a man with two convictions and an alcoholic history, and recalled the theft of property, including his beaver hat and twenty roubles. He concluded that the pituitary acted as a kind of individualizing mechanism: it determined the particular human image, not a universal image shared by all people. That judgment sharply limited the promise of the procedure. Transplantation could produce humanization, but it did not allow the surgeon to select an abstract model of humanity independently of the donor whose organs supplied the transformation.

The experiment thus challenged the ambition behind Preobrazhensky’s interest in improving the human race. The result did not furnish a reliable route to eugenic improvement; it reproduced the specific human traits associated with the donor. In the professor’s account, the pituitary was powerful precisely because it carried individual difference into the new being, while offering no guarantee that the resulting person would embody intelligence or social advancement.

Social Consequences and the Question of Responsibility

Humanization quickly raised questions that the scientific description could not settle. When the new man called Preobrazhensky “Dad,” the professor rejected the assumed familiarity. The term nevertheless captured a genuine tension: the professor had created the conditions for the man’s existence, but biological or experimental creation did not automatically establish a mutually accepted father-and-son relationship. The new being invoked the operation in arguing that he had not requested it, while Preobrazhensky pointed to the dog’s former life as an alternative to human existence.

That conflict turned scientific authorship into a question of responsibility. Preobrazhensky could call his creation an unnatural phenomenon or artifact when asked where it should be registered, yet the being before him spoke, asserted claims, and sought ordinary social standing. Later, Sharikov announced that he intended to marry the household typist and have her live with him, adding that Bormenthal would have to leave the waiting room. The announcement shows the transformation extending beyond speech into attempts to establish a household and make claims over shared living space.

The operation’s consequences therefore exceeded the laboratory. Its result had to be addressed through names, social relationships, registration, money, and domestic arrangements. The new person’s human form did not resolve how others should treat him, while the professor’s role as creator did not provide a settled social or familial bond. The experiment’s central paradox remains: it could bring about human formation, but it could not predetermine the identity, character, or relationships of the person formed.